The Effects of Drug Use, Depression, and Social Factors on HIV/HCV Care Continuum among PWID in Urban Areas: A Social-Network Perspective Project Abstract Social networks, depression, drug use, and drug use stigma can impact engagement in HIV/HCV care continuum among PWID. However, it is yet to be understood how these factors mediate/moderate HIV/HCV treatment outcomes (Wolfe et al., 2017). The parent grant, R01DA040488, focuses on outcomes of HIV/HCV medical behaviors and risk behaviors and suggests that stigma, depression, and social network factors are mediators/moderators of HIV/HCV care. This supplement is a logical extension of the parent grant as the proposed work investigates the extent in which stigma, drug overdose, depression, and social network factors may moderate or mediate HIV/HCV care outcomes, a critical component that is not directly explored in the aims of the parent grant. Past behavioral interventions on PWID in Baltimore, where the parent grant is based, showed significant decreases in risky drug use practices. However, such behavioral interventions have had little success in significantly increasing medical care utilization and adherence to anti-viral therapy among PWID (Purcell et al., 2007). As such, research that identifies the extent to which salient factors may hinder positive treatment outcomes among PWID is needed. Thus, we propose to evaluate the impact of social network, depression, drug use, and drug use stigma on HIV/HCV care. We define HIV/HCV care as seeing an HIV/HCV care provider, receiving a prescription for HIV/HCV medication, and achieving sustained viral suppression. Using baseline data from the social network-based, randomized control trial of 500 opiate users, we will prospectively examine the above components of HCV care at 6 and 12-months.